Experiments with Small Numbers of Observations

This is a report on part of an experiment that is under way having for its objective the determination of (a) the extent of divergence from theoretical values of probability in small samples, and (b) the extent of divergence from theoretical values of probability as computated by Student\u27s method if the sample is drawn from a non-normal distribution

Disproportionate subclass numbers in tables of multiple classification

Under the stimulus of some of the newer methods of experimentation there is a decided tendency toward the grouping of classes of data into smaller and more homogeneous sub-classes. The weights of swine, for example, may be simultaneously classified according to the sex as well as the litter of the individual animals. Corn yields may be entered in a three-way table by applying the criteria of variety, treatment and soil type. From the resulting tables of multiple classification can be derived information not only of the main effects, such as sex and litter, but also of the interactions between them. Analysis of variance is the most convenient and effective method of reducing such classified data to summary form and testing the significance of the various effects

A Statistical Test of Experimental Technique

The phrase experimental technique is used in a largely inclusive sense in this paper. A more precise title would be A Statistical Test of Homogeneity. The reason for the more flexible phrase will be apparent, I trust, as the argument progresses

Statistical Control of a Grading System

Statistical Control is a phrase which is very popular in business circles. What does it mean? Let us examine two types, the statistical control of the quality of a manufactured product, and the statistical control of a purchasing department. In the former case, over a sufficient period of time, records are made of the number of defects per 1000 (say) found in the product manufactured. From these records statistical standards are set up consisting of the averages and distributions of the occurrence of defects. By comparing any subsequent sample with such standards, the statistician is able to assert that the occurrence of defects in this sample is within or without the ordinary limits of random sampling. If without, the manufacturing department is notified of the excess of defects and is expected to remedy the situation. In the case of the purchase of commodities, the standard (price to be paid) is ill defined or lacking. In this type of control, the distinguishing feature in the estimation of the proper price to be paid is the collection and use of a group of statistical facts concerning correlated, independent variables. Some such are (1) the trend of prices in the commodity itself with due attention to seasonal and cyclical fluctuations; (2) the level of general commodity prices, (3) the facility of credit, etc. From such data, the statistician fixes an average price to be paid for the commodity and a proper time for its purchase

Statistical methods : Applied to experiments in agriculture and biology

xiii, 534 p.; 23 cm

Disproportionate subclass numbers in tables of multiple classification

Under the stimulus of some of the newer methods of experimentation there is a decided tendency toward the grouping of classes of data into smaller and more homogeneous sub-classes. The weights of swine, for example, may be simultaneously classified according to the sex as well as the litter of the individual animals. Corn yields may be entered in a three-way table by applying the criteria of variety, treatment and soil type. From the resulting tables of multiple classification can be derived information not only of the main effects, such as sex and litter, but also of the interactions between them. Analysis of variance is the most convenient and effective method of reducing such classified data to summary form and testing the significance of the various effects.</p